(1) Technical Field
This invention is concerned with methods for making semiconductor devices, and more particularly, to the curing of photoresist films used in such fabrication.
(2) Description of the Prior Art
U.S. Pat. No. 5,431,700 issued Jul. 11, 1995 to Ben J. Sloan discloses a wafer baking and chilling apparatus which heats the wafers with a bake plate from the front side. The invention also used gas flow.
U.S. Pat. No. 5,306,653 issued Apr. 26, 1994 to Chang W. Hur shows a method of baking photo resist to make it flow to a desired width.
U.S. Pat. No. 4,814,243 issued Mar. 21, 1989 to David H. Ziger shows an image reversal process using a bake process in an oven.
A wafer for the manufacture of semi-conductive elements is subjected to numerous sequenced operations during photolithography enables the fabrication of all its circuit elements. The use of a thin layer of photo resist on a wafer's surface in conjunction with photolithograhic masks provides the means to transfer the various masking layers onto the semiconductor wafer. The photolithographic mask selectively exposes a portion of photoresist film to actinic light while leaving the masked portion unexposed. The exposed portion makes the photoresist soluble in a base solution and insensitive to light. The unexposed portion is insoluble in the base solution and is photo sensitive.
The development of highly integrated circuit patterns with line widths and spacing in the submicron ranges places increasingly higher demands on image resolution capabilities of the photoresist. Processes involving film thickness, thickness uniformity, resist baking, and intermediate handling have become critical steps in the manufacturing of high speed integrated circuits.